Stuffed rat head tests how to scan a waking brain

You might expect to see a stuffed animal head on a wall, but in this video a stuffed rat's head is attached to a moving robot. The futuristic mount is being used by researchers Andre Kyme and Roger Fulton at the University of Sydney, Australia, to test a new motion tracking device that will allow an animal's brain to be scanned while it's awake.

To study diseases in detail, scientists often probe rodents with PET scans before progressing to humans. Typically, rats are put under before a scan, because results can be skewed if they move around. But anaesthetics can affect results since they can change how the brain works.

To get around this, Kyme and Fulton turned to motion tracking, which allows rats to be scanned while awake. In their first trials, they used a device that follows physical markers placed on a rodent's forehead (see video above). Although the tracking was accurate, the markers caused problems. "Rats don't like having things stuck to their fur and will generally attempt to remove them," says Kyme.

The team therefore created a new system that tracks distinctive natural features on a rat's head. A computer algorithm detects unique landmarks, like a blemish in the rodent's skin or the corner of an eye, based on visuals received from four cameras. "When the same feature can be seen from multiple views, its 3D location in space can be determined," says Kyme. "We do this for many features on the head at around 30 frames per second."

The device, which was successfully tested with taxidermied specimens, can estimate the movement of a rat's head with 10 times the accuracy of designs using markers. The team is now testing it on live animals. If successful, the method could be scaled up for use in larger animals, such as monkeys and humans. "It would be feasible to image a person while they were on a treadmill," says Kyme.